Mobile terminals, such as a cell phone, a smart phone, a tablet terminal and others, are generally provided with a power storage device such as a battery, and each device mounted on a mobile terminal receives a power from the power storage device to operate.
One of points to be considered when designing a mobile terminal is that a situation can occur in which the power supply from the power storage device is suddenly cut off. The most typical example of situation in which the power supply from the power storage device is cut off is the case where the power storage device is removed from the mobile terminal by the user. Many mobile terminals are designed in such a way the user can exchange the battery, and in a case of such a design, the user may remove the battery from the mobile terminal. In addition, even if the mobile terminal is designed in such a way the battery cannot be easily removed by the user, the battery may be removed by an examiner while a process of product inspection.
When a power supply from a power storage device is suddenly cut off, a system operation cannot be continued and an abnormal shutdown occurs. It is desirable to design a mobile terminal in such a way no abnormal operation is caused even if an abnormal shutdown occurs due to a sudden cutoff of power supplied from a power storage device.
A mobile terminal is generally provided with a panel displaying device such as a LCD (Liquid Crystal Display) device or others; therefore, it is desired, in a case where an abnormal shutdown occurs, that no abnormal operation is caused to the panel displaying device either. Against such background, the Inventor is studying about suppressing abnormal operations in a panel displaying device when an abnormal shutdown occurs.
One of abnormal operations studied by the Inventor is a residue of charge in a display panel of a panel displaying device. In general, in a case where a system is normally shut down, the system operation is stopped after a discharge of charge in the display panel is performed. On the other hand, in a case where an abnormal shutdown occurs due to a cutoff of the power supply from the power storage device, a situation may occur in which the system operation stops with a residue of charge in the display panel of the panel displaying device. If a charge is left in the display panel of the panel displaying device, a burn-in may occur in the display panel and an abnormal display may appear on the display panel.
Against such background, it is desired to be provided a technology to suppress abnormal display on a display panel in a case where an abnormal shutdown occurs due to a cutoff of a power supply.